Pratt & WhitneyJFTDI2
AERO ENGINES 1962
1024 FLIGHT International, 28 June 1962
DOD; Boeing were given a paid study contract to switch from the GE
MF295 (q.v.) to the TF30. Although bigger and heavier than the other
engines considered, the TF30 was a Pratt & Whitney product, and this
appears to have been a major factor in its selection. The engine is thus
now a focal point in what will probably become the largest aircraft
programme in the US, and total engine purchases are expected to reach
$800m over eight years. The manufacturer's designation for the TFX
engine is JTF10A-20. Installed in the Air Force F-111A it is expected
to weigh about 3,5501b with afterburner and variable nozzle, but without
any deflection system (which was not asked for). Details of the engine
are classified, but it is said to have a zero stage on the fan and to be
rated at approximately 12,0001b dry and 19,5001b with reheat in both
hot and cold flows. It is thus very closely related to the TF-106. Several
JTF10 experimental engines are running, and one has flown under a
B-45. The A-20 version has yet to be built, and it is anticipated that it
will need about two years to bring it to the production stage.
JT11 Financed by the Navy as the J58, this single-shaft turbojet
is in the 30,0001b class and is specifically designed for cruising Mach
numbers over 2.5. A number of experimental units have been run at
West Palm Beach, and although this engine is no longer an active
project it has been instrumental in the development of supersonic-
transport propulsion systems.
The first bench run of a prototype engine was originally scheduled
for April 1961, but was delayed until late May. The first 150hr test was
announced in December, when total running exceeded l,000hr. Flight
testing was due to begin last autumn, with an engine slung beneath a
B-45, but the start of such flying has yet to be announced. In spite of
this delay, and of fairly severe stalling experienced in the h-p compressor,
the overall programme is approximately on schedule, with about ten
engines having now logged well over 4,000hr. Simulated altitude
testing in the Willgoos laboratory has yielded better than the estimated
performance. Prototype deliveries to Boeing for airframe testing are
due this year—one is already flying, hung on the rear of the "-80"' —and
production deliveries are scheduled for 1963 (originally "in the first
half" of 1963). Pratt & Whitney are looking for further commercial
applications, and are especially considering the Caravelle 10B and the
BAC One-Eleven (for which they have proposed a derated JT8D).
List price of the JT8D-1 is due to rise from the current 8210,000 to
8231,000 by 1965.
Military JT8D Although proposals have been made to the US
Government—some, one would think, with jet deflection along the lines
of the Pegasus—there is no announced application. Earlier this month,
however, the JT8D was chosen as the basis for the powerplant for the
Swedish Saab-37, and this is discussed on page 1013.
JTF10 Today one of the most important aircraft engines in
America, this turbofan has a long and chequered history. The basic
design incorporated major puts of the JT8 (J52) turbojet, and was
evolved in 1957 to meet anticipated commercial and military require
ments. The first detail investigation began in 1958, in which year
Douglas chose the JTF10A-1 as the powerplant of the projected DC-9
four-engine short-haul airliner. The A-l was a flat-rated unit delivering
8,2501b at up to 90°F, with promised growth to 9,5001b on a standard
day. During 1959 Douglas agreed the use of a full-length annular
by-pass duct and reverser, and the dry weight of the bare engine came
out at 2,1101b.
The first run of a prototype engine took place in that year, and proto
type delivery was then scheduled for April 1961. Despite the lapse of
this application, development of a commercial JTF10 has continued,
and the most important version at present on offer is the JTF10A-6,
some figures for which are given in data table 2. This powerplant is
specified for the Douglas 2086, and is available for the BAC One-Eleven.
In each case the engine is started by its 40kVA alternator and c.s.d., and
exhausts through a pneumatically actuated reverser. L-p bleed air is
used directly for cabin pressurization, and the same air is tempered
with an h-p bleed for ice protection.
Military TF30 By 1960 the US Navy had welcomed the JTF10
as the ideal high-pressure engine for the subsonic Missileer, the carrier
aircraft for the Eagle missile. When this weapon system was cancelled
in April 1961, the Navy continued to finance the 10,0001b TF30-2
turbofan, and are said to have injected about $30m to date. At the same
time the engine appealed greatly to SNECMA, United Aircraft's
French licensee, who were seeking a propulsion engine capable of com
peting in the forthcoming NATO V/STOL competitions. Pratt &
Whitney have since collaborated with SNECMA in the development of
the TF-104 and TF-106 (q.v.). Meanwhile the US armed forces were
formulating their requirements for a new "all can do" tactical fighter
and strike aeroplane, and the TFX competition was instituted. After
one of the largest battles ever fought by the US aircraft industry the
Department of Defense last January chose the entries submitted by
General Dynamics Forth Worth and The Boeing Co Wichita. GD had
based their submission on the TF30, and this was the engine chosen by
JT12 Designed by Canadian Pratt & Whitney, this single-shaft
turbojet has proved itself a most competitive unit for light military and
executive aircraft. First run in May 1958, it completed its 150hr quali
fication 16 months later and has been in production at Hartford for two
years. Although a supersonic afterburning version is available, the
production applications are for non-reheat engines in the T-39/T3J
Sabreliner, C-140/JetStar and the Fairchild SD-5 drone. Price of the
JT12A-6 is $69,000, and the 3,3001b A-8, specified with SNECMA
reverser for the Mystere 20 transport, is 880,000. The same gas pro
ducer is used in the JFTD12. Military designation of the engine is J60.
JFTD12 By adding a two-stage free power turbine at the rear
of the JT12 turbojet Pratt & Whitney have evolved a turboshaft unit
with a very competitive brochure performance. This performance has
been confirmed by bench testing over the past two years, and on May 9
the engine flew as the powerplant of the Sikorsky S-64 Skycrane. Two
JFTD12s are geared to the helicopter rotor system, with their exhausts
turned outboard. The industrial FT12 is rated at 3,000 s.h.p.
USSR
It is not generally realized that about a dozen types of Russian engine
are in daily use in Western and "neutral" countries, including the
19,1801b RD-3 (AM-3M) turbojet, the 4,015 e.h.p. AI-20 turboprop,
and many types of piston engine. In recent weeks considerable interest
has centred around the decision of the Indian Government to con
sider the VK-7 turbojet, developed under the leadership of Vladimir
Klimov, as a possible powerplant for the developed M2 version of the
Hindustan HF-24 fighter. The VK-7 is said to be a development of
the VK-5 (M-205), which is rated at 6,5001b dry and 8,8181b with reheat.
The VK-5 powers the Mig-19 and Yak-25 supersonic fighters, and its
total production must exceed 20,000 engines. The VK-7 is not known
to have been used in any specific Russian aircraft, although it may well
be fitted (with centrebody intakes) in supersonic attack machines
clearly derived from the original Yak-25. With a diameter of some 33in,
the engine is almost installationally interchangeable with the Orpheus,
but Indian technicians are reported to have suggested a series of modi
fications as a result of studying several VK-7s which were shipped to
India earlier this year. According to one source, the proposed modi
fications would require 18 to 24 months to effect.
Soviet Aviation Day last July provided a glimpse of the supersonic
"Bounder" prototype, with four engines arranged with direct pitot
intakes. The inboard engines of this aircraft are estimated to be rated
at some 30,0001b dry and 45,0001b with reheat, and are probably
versions of the Soloviev D-15, rated at 28,6601b. On the same occasion
the Kamov Vintokryl convertiplane was seen for the first time, and the
recent speed-record submission to the FAI describes it as being powered
by a pair of 5,700 h.p. TB-2 turboshaft engines, geared to both the
propellers and rotors with the free-turbine output from both engines
interconnected. In contrast, the TB-2BM engines of the even larger
Mi-6 helicopter are rated at only 4,635 s.h.p.
There have been unofficial reports concerning the turboshaft engines
fitted to the new Mil V-2 and V-8 helicopters, but none appears to
be reliable; photographs suggest that the V-2 has two engines of about
500 s.h.p. and the V-8 a single engine of about 3,000 s.h.p.
No reliable details are yet available on the turbofan engines of the
Tu-124 and Tu-124A airliners, although it is suggested that they are
Soloviev units rated at 8,5001b. The engine of the An-24, now coming
into service, is the 2,500 s.h.p. AI-24, and preliminary information
suggests that it is a single-shaft axial unit. Finally, L'yulka has pro
duced a turbojet weighing 50.71b and rated at 1211b thrust, which is
flying in the An-13 sailplane.